The present invention refers to a device for the treatment of flat materials, more particularly for embossing or calendering foils of paper, metal, or a combination of these materials, comprising at least a pair of cylinders between which the flat material is passed under pressure. Devices of this kind are commonly used for calendering and/or embossing packaging films. In this process, embossing rolls, in particular, have to be pressed against each other with a relatively high pressure in order to obtain the desired deformation resp. structure of the flat materials. Swiss Patent Application No. 03 102/93 refers to a method for fashioning flat materials in which the flat material is calendered on its entire surface in a first step and locally flattened in a second step, in such a manner that flat, glossy aeras in the form of emblems, trademarks or the like appear on the calendered material. The embossing rolls for this or for similar treatments of flat materials have to be pressed against each other with a relatively high pressure, resulting in a risk of an uneven effect of the pair of rolls on the flat material. This high pressure may result in the material becoming jammed or folded if the axes of the rolls are not adjusted to each other in such a manner that they exert an even pressure across the entire width of the flat material independently of irregularities of the material such as transversal differences in thickness of a paper web. However, adjustment errors of the calendering or embossing rolls may also result from the tolerances of the machine. Also, deviations from the correct mutual position of the roll axles in the travelling direction of the flat material, perpendicular to the direction of the roll pressure acting on the flat material, are quite common. Adjustment errors of this kind also lead to quality defects and to a considerable reduction of the lifetime of the rolls, especially in the case of calendering or embossing rolls having interlocking calendering or embossing members, respectively. Until now, in order to prevent such errors, the operation of the rolls had to be continuously monitored and manually readjusted if necessary. These adjustments require highly experienced personnel, on one hand, and lead to machine downtime, on the other.